Broken crank

[Flyin Brian]

I agree. If you wanted to get scientific about it you could take it to a metallurgist and get some tests run but that would be expensive unless you know one. If you knew someone with a hardness tester you could check the hardness in the discolored area versus the rest of the crank. It would be interesting to see if the heat effected area was harder or softer than the rest of the crank. In any case I would not re-use a part that was discolored that bad.

 

[Nick Micale]

This is the remains of a BMS crank that gave up at 3000 RPM at the break-in on a rebuild years ago, but the rod journal had been turned, and certainly had prior damaged?

This was before the advent of China cranks and any forged crank was a rare find, and I think it cost ~$1800.

The lesson learned was NEVER use a repaired crank in a performance engine build.

 

[ericwiebrecht]

The #1 rod bearing gets oil from the #1 crank journal, and since your crank broke through the web that contains the oil hole, it severed the pressure feed to the rod bearing.

 

[TurboBuRick]

When a crank breaks before put under any real power, something was up before it went in motor. Somehow, somewhere it took a hit. I would bet a good buck on that....

Rick